1. Field
The present embodiments relate to a magnetic head assembly bonding electrode pad of slider and electrode pad of flexible wiring substrate together by solder.
2. Related Art
In the related art, a magnetic head assembly used in a hard disk drive (HDD) includes a slider that has a head element mounted therein. A flexure, which is formed of a resilient thin metal plate, elastically supports the slider. A flexible wiring substrate, which is bonded to the surface of the flexure, electrically connects the head element and an external circuit system. The flexure is fixed by spot welding to a load beam. In this kind of magnetic head assembly, an electrode pad of the head element of the slider is bonded by gold ball bonding to an electrode pad of the flexible wiring substrate in an orthogonal relationship. Recently, in order to respond to the trend in that a bonded region (the size of the electrode pad and the interval between the electrode pads) is narrowed, a solder ball bonding method using a solder ball which has a smaller diameter than that of the gold ball has been described in JP-A-2004-283911 (US 2004228036A1).
The solder ball bonding method can be performed by using a mounter of an SJB (Solder Jet Bonding) type in which a melted ball is spurted toward a bonded surface. By solidifying the melted ball, which is applied onto the bonded surface by the mounter, the electrode pad of the slider and the electrode pad of the flexible wiring substrate are bonded to each other. A surface protective layer composed of an Au film is formed on the surface (bonded surface) of the electrode pads of the slider and the flexible wiring substrate so as to increase solder wettability.
However, once the solder ball is applied in a wet state to the bonded surface, the solder ball is rapidly cooled and solidified before it sufficiently diffuses. For this reason, because of shrinkage deformation caused by solidification of the solder ball, the position (roll angle, pitch angle) of the slider is significantly changed before and after soldering. The positional change may deteriorate floating characteristics of the magnetic head slider, for example, output characteristics.